The goal of this Rett Center Core is: 1) to coordinate and unite the individual Projects into an integrated Research Program Project, 2) to facilitate the successful completion of the specific aims of the proposed projects, and 3) to initiate the design and development of future projects. The Core will ensure the integration of the Research Program Project as a whole by promoting dynamic interactions among individual investigators and with other scientists, particularly our External Advisors. These interactions will promote and ensure the growth of the Research Program Project by sharing information, critiquing current research efforts, and formulating new hypotheses and research designs. The research efforts of this Program Project will be closely monitored by members of the Core that include Drs. Glaze, Armstrong, Dunn, and Ms. Schultz, most of whom have been involved in this Research Program Project since its inception, and ensure the continuity of our research efforts. The Core is the center for patient identification, education, follow-up and research protocol enrollment. Members of the Core will provide longitudinal assessment of a large, well defined and established group of RS individuals, thereby providing clinical profiles to correlate with the research efforts of the individual projects. Under the direction of Dr. J.K. Dunn, the Core provides statistical design and analysis support and continues to develop an already extensive data base that is used regularly not only for patient identification and selection, but also for the generation of hypotheses. These activities of the Core ensure integration of the Research Program Project as a whole by bringing together our multidisciplinary team to study in an integrated the many dimensions of RS.